This section provides background information related to the present disclosure which is not necessarily prior art.
Thermal spraying is a technique used for coating a substrate, for instance, to protect the substrate against corrosion. Cold spraying is a type of thermal spraying in which a stream of solid particles is accelerated to high speeds by a carrier gas through a nozzle toward the substrate. The particles have enough kinetic energy upon impact with the substrate to deform plastically and bond metallurgically/mechanically to the substrate to form a coating.
The particles are accelerated to a critical velocity such that the coating can be created. This critical velocity can depend on the properties of the particles and the substrate (i.e., deformability, shape, size, temperature, etc.).
The particles can also be heated by the carrier gas in order to make the particles more plastic to deform upon impact. The amount of heat supplied from the gas can depend on the properties of the particles and the substrate.
Excessively hard substrates (e.g., tool steel) can be difficult to coat by cold spraying. This is because the substrate may not deform enough to allow the particles to bond and form the coating. The impact of the particles can also cause cracking of the substrate.
In addition, excessively soft substrates (e.g., polymers) can also be difficult to coat using cold spraying techniques. For instance, these substrates may be damaged by impact of the particles and/or the high temperatures of the gas used to accelerate the particles.
Furthermore, some particles may not be suitable for cold spraying. For instance, excessively hard particles (e.g., ceramics) may not deform sufficiently upon impact with the substrate to bond and coat the substrate.